1. Field of the Invention
The present invention relates to a printing system, a thermal printer, a printing control method, and a data storage medium. More particularly, this invention relates to a printing system, a thermal printer, a printing control method, and a data storage medium that apply a printing process appropriate to the type of thermal paper that is loaded in the printer.
2. Description of the Related Art
Line thermal printers and other types of thermal printers (xe2x80x9cprintersxe2x80x9d below) have one or more rows of plural independently driven and heated heat elements. Such printers print by selectively driving (heating) the heat elements to heat a particular spot on thermal paper disposed opposite the driven heat element, thereby producing a desired color on the thermal paper. The colors produced in thermal paper used in this type of printer differ according to the amount of heat energy (applied energy) applied by the heat element. It is therefore possible to change the colors produced on the thermal paper by controlling and changing the applied energy. This is accomplished by varying the pulse width of the current pulses applied to the heat elements.
There are two general types of thermal paper capable of producing two colors, additive color paper (additive type color paper) and subtractive color paper (subtractive type color paper). If the color produced at a low applied energy level is the first color and the color produced at a high applied energy level is the second color, the first color is red or another bright color and the second color is black or another dark color with additive color thermal paper. That is, the second color is the color achieved by adding a specific color to the first color. With subtractive color thermal paper the first color is black or other dark color and the second color is red or another bright color. In other words, the applied energy characteristics of additive color and subtractive color thermal paper are directly opposite. In addition, thermal paper capable of producing three or more colors has been recently proposed.
The operating system used in a computer or other type of data processing terminal provides centralized management and control of system resources shared by various application programs. A software driver is provided for each system resource (such as a peripheral device), and the data processing terminal operates as a device (driver) for managing the resources by running the driver programs.
A printer is one such system resource. An application program running on the data processing terminal is able to print from the printer using a procedure such as described below.
(1) The application program (simply xe2x80x9capplicationxe2x80x9d below) sends a print request containing the data to be printed to the operating system. More specifically, the application invokes a system call to the operating system, specifying the address in memory where the print data is stored and such parameters as the amount of data to print.
(2) The operating system invokes a service routine provided by the printer driver, and passes various print data parameters.
(3) The printer driver service routine displays the current printer settings on a display or monitor connected to the data processing terminal, and prompts the user to confirm the printer settings. The settings typically include the paper size and orientation, for example.
(4) If the settings are confirmed, the service routine generates a print command for the selected printer based on the print data and printer settings, and then sends the print command to the printer.
It will thus be obvious that the printer driver functions to relay printer settings and print commands from the application to the printer. The printer driver thus functions as the control unit performing this function using a program containing commands for achieving this function.
By incorporating the printer driver program into a computer or other data processing terminal, the data processing terminal also functions as a printer driver device.
Two-color thermal printers have conventionally been limited to printing with either additive color thermal paper or subtractive color thermal paper. When a thermal printer using one type of thermal paper becomes dominant in the marketplace, the type of thermal paper used by the dominant printer also tends to dominate, becoming widely available while demand for and supplies of the other type of thermal paper drop. For example, if a thermal printer that uses subtractive color thermal paper becomes the market leader, thermal paper supplies become dominated by subtractive color thermal paper while additive color thermal paper becomes less common and not as readily available.
Users of thermal printers that cannot use the type of thermal paper that is most readily available are thus inconvenienced by the need to look for the necessary type of thermal paper because supplies of that type have been reduced. A drop in the supply of that particular type of thermal paper also increases the cost of that particular type, making the paper more expensive for the user. Thermal printers that cannot use the type of thermal paper that is most commonly available are thus extremely inconvenient printers to use.
With consideration for this problem an object of the present invention is therefore to provide a printing system, a thermal printer, a printing control method, and a data storage medium able to apply a printing process appropriate to the type of thermal paper loaded when the paper is replaced.
We have researched various solutions for the problems of the related art described above. Through this research we found that printing control suitable for the type of thermal paper loaded in the printer can be achieved by determining the type of thermal paper placed in the printer when the paper is replaced. A function enabling the user to select the thermal paper type can be provided in the printer driver, for example, as a way of achieving printing control matching the type of thermal paper used in the printer.
Print control according to the type of thermal paper loaded in the printer can also be achieved by specifying the print pixel data buffers for separately storing print pixel data for each print color in the print data received from the host computer according to the type of thermal paper in the printer, and controlling the applied energy used to print the colors according to the type of thermal paper.
Furthermore, by controlling printing according to the type of thermal paper used, a thermal printer according to the present invention can use different types of thermal paper, including whichever type of thermal paper is most commonly available.
The invention resulting from this research is described below.
A printing system according to a first aspect of our invention has a printer driver for executing a print request from an application program running on a data processing terminal according to a loaded type of thermal paper; and a thermal printer for controlling printing requested by the application program using the printer driver according to the type of thermal paper loaded when the paper is changed.
The type of thermal paper used in this printing system is preferably monochrome thermal paper, two-color subtractive color thermal paper, or two-color additive color thermal paper.
A thermal printer according to another aspect of the present invention and used in the preceding printing system has (a) a thermal print head having a plurality of heating elements, (b) a paper information storing section for designating (c) a paper type selected from a type of additive two color thermal paper and a type of subtractive two color thermal paper, (d) a first pulse width modulation section for selectively controlling the energy to be applied to each heating element in accordance with energy levels required to obtain the two colors of the subtractive two-color thermal paper, (e) a second pulse width modulation section for selectively controlling the energy to be applied to each heating element in accordance with energy levels required to obtain the two colors of the additive two-color thermal paper, and (f) a buffer selector for selecting either the first or the second pulse width modulation section based on said paper type information.
This printing system also has (g) a paper type determining unit that includes an input control unit that selects either an automatic determining mode or a manual-determining mode.
In this system the paper type determining unit includes a printing control unit that performs the printing by energizing the thermal print head with at least two predetermined levels of applying energy and a printed color detection control unit that reads the printed result to detect the color.
A thermal printer according to another aspect of the present invention and used in the preceding printing system has (a) a data receiving section that receives the print data from a host computer, (b) a paper information memory section that stores at least a relationship between first and second colors and different energy levels to be applied to produce each color, (c) a first print data storing memory section that stores print data for the first color that can be produced by the low energy level, (d) a second print data storing memory section that stores print data for the second color that can be produced by the high energy level, (e) a data input control means for determining one of the print data storing memory sections based on the information stored in the paper information memory section when the print data is received from the host computer, (f) a pulse generating section that generates at least three pulses, (g) a history data storing section that stores at least one occurrence previous print data of each color, (h) a logic circuit that produces a current time period for driving each heating element by choosing one or more pulses corresponding to the present print data and the history data, (h) a driving section that drives each heating element with a low energy level in accordance with the data stored in the first print data storing memory and with a high energy level in accordance with the data stored in the second print data memory section.
In this printer, the data input control unit includes an address exchanging unit that exchanges the addresses of the print data storing memories based on the information stored in the paper information memory section that designates the type of the thermal paper.
In this printer, the paper information memory section designates one of the paper types including subtractive color thermal paper and additive color thermal paper.
The printing system of this invention also has a printer, a print data receiving unit that receives print data from an application program on a host computer, a first print data storing memory that stores the first color print data of a first color produced by a low energy level, a second print data storing memory for storing the second print data of a second color produced by a high energy level, a data storing control unit that selects one of the first and second print data storing memories when inputting the first or, second color print data based on the information stored in the paper information storing section, a printer driver that selectively sends the color print data to the printer, and the print data receiving unit, first print data storing memory, second print data storing memory, data storing control unit and printer driver are included in the host computer.
A printing control method for controlling a thermal printer according to further aspect of this invention comprises (a) a print data receiving step of receiving a print request and print data from an application program, (b) a step of storing the received print data by each color of at least first and second colors to a predetermined memory section to define first and second color print data, (c) a step of determining a paper type of a paper installed in the printer, a step of determining each color data to be produced by a low energy level or high energy level, (d) a step of storing the first color print data in a first print data storing buffer to be energized by a predetermined low energy level, (e) a step of storing the second color print data in a second print data storing buffer to be energized by a predetermined high energy level, and (f) a step of controlling a heating element by driving the heating element in accordance with the color print data stored in the first print data storing buffer in a predetermined first current time period and driving the heating element in accordance with the color print data stored in the second print data storing buffer in a predetermined second current time period that is greater than the first current time period.
A data storage medium according to a further aspect of the invention records (stores) a computer-executable program for executing the printing control method steps of the invention as described herein.
This data storage medium is preferably a Compact Disc (CD), floppy disk, hard disk, magneto-optical disk, Digital Versatile/Video Disc (DVD), magnetic tape, memory card, or other computer readable storage medium.